On the famous Holmes and Rahe Stress Scale, where death of a spouse is 100 “Life Change Units” and getting fired is 47, adding a new baby to the family clocks in at 39. Many new dads think that number should be a lot higher. They may be right. New research shows that entering fatherhood can indeed bring many changes to a man’s mind and body.

For starters, there’s the weight gain. The average first-time father packs on an additional two kilos if he lives with his children and slightly less if he doesn’t, compared to comparable non-fathers. Researchers at Northwestern University believe that the difference is partly due to our fatherly habit of helping clean our kids’ plates, especially of things like leftover pizza crusts.

In an article in the American Journal of Men’s Health, Dr. Craig Garfield and colleagues note that there is a bit of a paradox because “prior research reports becoming a father is a time when men attempt to improve their diets, increase physical activity, decrease alcohol use, and lower risk-taking behaviour.” Apparently those good intentions don’t translate into reality, because the body mass index of fathers soars compared to men who never have children. According to Garfield’s 20-year project involving over 10,000 American men, “the increase in this study is evidence that these changes in health behaviours may have little impact.”

Some of that weight gain may also be due to the stress of fatherhood. New household routines, diaper changes in the wee hours, and mother’s preoccupation with the new family member, can all take a toll on a man’s emotional state. Postpartum depression isn’t just for women any more.

Daniel B. Singley of the Center for Men’s Excellence in San Diego, CA writes that “recent research has shown that roughly 10 per cent of new dads experience mental health difficulties including depression and anxiety”. Yet, he notes, postpartum depression research has focused almost exclusively on mothers. Some of the consequences of untreated mental health issues in men “include a reduction in fathers’ engagement with their babies, which has been associated with greater stress and other poor long-term psychosocial outcomes in their children.” So, for everyone’s sake, it’s a good idea to watch how dad is feeling about the whole baby thing.

Is there an optimal way to divide parenting chores? Psychologists Jennifer Fillo and Jeffrey A. Simpson of the University of Minnesota don’t see a “one size fits all” solution. Their study of 137 American couples found that how the child care tasks are divided doesn’t necessarily predict satisfaction. In this study, mothers did almost twice as much of the work as fathers, but “women seemed to handle the transition to parenthood and child care tasks better than most men.”

These researchers single out a particular group of people who are at risk in the new parent setting. People with “attachment avoidance” are deeply distrustful of close relationships, often because of previous experience of rejection. “The chronic stress associated with the transition to parenthood,” they write, “which involves negotiating new life roles and tasks with one’s romantic partner while also providing constant care to a highly dependent infant, should be especially taxing on highly avoidant people.” They write that these people “view both their child and the demands of new parenthood as restricting their autonomy and blocking their other important life goals”.

Asking a man, especially a highly avoidant one, to carry more of the burden of a baby can lead to disaster. “Not only do men — particularly highly avoidant men — react quite negatively to child care when they report completing more of it; their negative reactions appear to ‘bleed over’ and undermine their relationship satisfaction.” These researchers advise paying more attention to what’s going inside a new dad’s head now, to avoid problems later.

What if both parents are male? A fascinating study by David M. Huebner of the University of Utah involved 48 gay male couples who were actively parenting children. Their findings “suggest that parenthood increases men’s commitment to their primary relationship while simultaneously decreasing time and energy for relationship maintenance, and generally decreasing sexual satisfaction.” They did not find parenthood causing greater infidelity or changes with respect to risky sexual behaviour. Just like heterosexual couples, “most men reported successfully coping with such changes through a combination of acceptance and revaluing what is important in their relationships”.

So, new dads, when it’s 4 a.m. and you’re looking for love and your partner is looking for that bag of diapers you were supposed to buy, take heart. Looking back, one of the most common words couples use to describe their early days with a new baby is … joyous.

Dr. Tom Keenan is an award-winning journalist, public speaker, professor in the Faculty of Environmental Design at the University of Calgary, and author of the new book, Technocreep, (www.technocreep.com).